Just over a third of adults age 18 to 65 in the United States received flu shots during the last flu season, according to new analysis by a nonprofit health advocacy group.

The study by Trust for America’s Health, released Tuesday, found that last year 45 percent of adults received flu vaccinations, which was up more than three percent over the 2011-2012 season, Reuters reports. But among younger adults, age 18-64, the percentage receiving the vaccine was 35.7 percent. More than half of children age 6 months to 17 years and senior older than 65 received vaccines.

According to the survey, vaccine rates were the highest in Massachusetts and lowest in Florida, A dozen states–Delaware, Hawaii, Iowa, Maine, Maryland, Massachusetts, Minnesota, Nebraska, North Carolina, Rhode Island, South Dakota and Tennessee–had vaccine rates higher than 50 percent. According to the CDC, flu is widespread in 35 states, and the CDC recommends everyone older than six months receive a shot.